The present invention relates to a recording and reproducing apparatus and a recording and reproducing method for recording and reproducing an information signal in and from a disk-like recording medium such as an optical disk or a magnetooptical disk.
A known disk-like recording medium (hereinafter simply referred to as an optical disk) in and from which an information signal is recorded and reproduced by laser beam is classified into a read-only optical disk called a compact disk, a write-once optical disk in which an information can be recorded once and a recordable optical disk in which an information signal can be not only reproduced but also recorded and erased.
In the read-only optical disk, tracks on which irregular patterns, i.e., phase pits are concentrically or spirally formed based on a recorded information signal are formed on one surface. Specifically, the read-only optical disk is composed of a disk substrate made of a transparent synthetic resin such as a polycarbonate or polymethyl methacrylate (PMMA), a reflecting film made of a metal such as Al or Au formed so as to cover the phase pits formed on one surface of the disk substrate and a protecting film formed on the reflecting film so as to protect the reflecting film.
When an information signal is reproduced from the read-only optical disk, laser beam emitted from a laser light source is irradiated on the read-only optical disk from the disk substrate side under being converged by an objective lens, reflected light bundle modulated by the phase pits on the optical disk is detected by a photodetector, for example, and converted into a detected signal having signal level corresponding to an intensity of reflected light bundle, thereby obtaining a reproduced signal of information signal recorded on the read-only optical disk.
A known recordable optical disk is a magnetooptical disk using a vertical magnetic recording material. The magnetooptical disk has a guide groove for guiding laser beam formed on one surface thereof and is composed of a disk substrate made of a transparent synthetic resin such as polycarbonate or PMMA, a recording layer made of a vertical recording material such as Te, Fe or Co formed so as to cover the guide groove and a protecting layer formed on the recording layer so as to protect the recording layer.
When an information signal is reproduced from the magnetooptical disk, similarly to the read-only optical disk, laser beam emitted from the laser light source is irradiated on the magnetooptical disk from the disk substrate side under being converted by the objective lens and a Kerr rotation angle of reflected light bundle modulated by the recording layer of the optical disk is detected to thereby obtain a reproduced signal of the information signal recorded on the magnetooptical disk.
The write-once optical disk is of a recording system using a physical chemistry change of dye, a hole-making recording system by a single layer, a hole-making recording system by a multilayer, a phase-change recording system and a bubble-forming recording system. Upon reproduction, similarly to the read-only optical disk, a laser beam (weak reproducing output power) from the laser light source is irradiated on the write-once optical disk from the disk substrate underside being converged by the objective lens. Then, reflected light bundle modulated by previously-recorded pits is detected by the photodetector and converted into the detected signal having the signal level corresponding to the intensity of the reflected light bundle, thereby obtaining an information signal recorded on the read-only optical disk.
As described above, when an information signal is recorded on and reproduced from the optical disk or magnetooptical disk, information recorded on the disk is read out by the optical head and sequentially processed, whereby recorded information is processed in real time and a reproduced signal is output. When on the other hand an information signal is recorded, a digitized information signal is supplied to the optical head, whereby desired recording information is recorded on a recording layer of an optical disk.
In the recording and reproducing apparatus, however, a reproducing drive device and a recording drive device are required in order to edit and record data on the disk, e.g., audio data. Therefore, at least two drive devices are required with the result that the overall arrangement of the recording and reproducing apparatus cannot be miniaturized.
In the recording and reproducing system, recording information and reproducing information are input or output in real time. As a consequence, information cannot be recorded and reproduced simultaneously within a single disk.
An existing drive device cannot edit data within the single disk while data is being input in real time.
In the disk drive, it is frequently observed that a so called track jump occurs due to application of external shock during recording and reproducing operation. If the disk drive is reproducing information, then a reproduced sound is lost. If the disk drive is recording information, then an information is recorded on a track different from a track on which the information signal should be recorded.
In particular, in the recording and reproducing apparatus for an optical disk and a magnetooptical disk, if a track jump occurs during a recording operation, then the laser beam irradiates a recorded track and recorded information will be damaged.
Therefore, it is customary that the recording and reproducing apparatus includes a housing in which a recording and reproducing unit is held through a buffer mechanism. Thus, an external shock transmitted to the recording and reproducing unit can be suppressed. However, in actual practice, it is very difficult to completely exclude a shock applied from the outside.